Outcome? I was going to say that suboptimal could refer to a case where we don't know if you'll reach your goal, but we can show (by common assumptions, let's say) that the action has lower expected value than some other. "Irrational" does not have such a precise technical meaning, though we often use it for more extreme suboptimality.

Yes, outcome. Look at what each word is actually describing. Irrationality is about process. Suboptimal is about outcome -- if you inefficiently but reliably calculate good strategies for action, that's being slow, not suboptimal in the way we're talking about, so it's not about process.